Laboratory Evaluation of Selected Medicinal Plant Extracts in Sugar Baits and Larval Food Against Phlebotomus Duboscqi Neveu Lemaire (diptera: Psychodidae), A Vector for Cutaneous Leishmaniasis in Kenya

Abstract

The efficacy of Tagetes minuta (Asteraceae), Acalypha fruticosa (Euphorbiaciae) and Tarchonanthus camphoratus (Compositae) extracts were evaluated for the control of Phlebotomus duboscqi while incorporated in sucrose. This is the first time plant extracts have been used in sucrose baits against sand flies as opposed to environmentally unfriendly synthetic insecticides. Materials and methods; The plants were collected from Marigat area, Baringo district in the Rift Valley Province of Kenya, an endemic area for leishmaniases. Extraction was done using N-hexane, dichloromethane, ethyl acetate and methanol. Results; The extracts showed significant mortality (P< 0.05) to both males and females and had comparable LD50 values in Tagetes minuta and Acalypha fruticosa extracts bioassays. The lowest LD50 value for females was 10.6mg/ml in ethyl acetate bioassays in Tagetes minuta and Acalypha fruticosa extracts, while the highest was 12.0 mg/ml in Tagetes minuta methanol extract. Males had the lowest value of 9.9mg/ml in Tagetes minuta methanol extract, while the highest was in Acalypha fruticosa methanol extract with a value of 15.5mg/ml. Results however showed that there was no significant mortality (P> 0.05) difference between males and females but mortality significantly differed (P<0.05) at various concentrations. Tarchonanthus camphoratus and combined extracts however showed weaker insecticidal properties than from separate extracts. Feeding the larvae using extracts in larval food and plain powders nonetheless revealed no larvicidal properties in the plant samples. Conclusion; The results showed potent properties and may guide future research initiatives aimed at controlling sand flies using sugar baits as alternative approaches to conventional methods.